Process of producing shell forgings and the like



. 2,251,094, of July 29, 1941, in the name of Claude a mandrel of thediameter and nose contour dedesign. The slug is then partially piercedto form tions and using a number of mandrels in teachings of the presentinvention, the. cross-' parting from. the scopeof the .invention,. a'sde- Patented May 4, 1943 7 2,318,069

UNITED STATES PATENT OFFICE Stevenson Findlater, Pittsburgh, Pa.,assignor to gational Tube Company, a corporation of New ersey NoDrawing. Application August 17, 1940, Serial No. 353,151

1 Claim. (Cl. 29-121) This invention relates to producing shell forgsidediameter and wall-thickness of the forging, ings and the like.eliminates the variations in the diameter and In the manufacture ofshell forgings and the wall-thickness which are inherent in tubularlike, a slug of proper size is heated, inserted into articles in whichthe final wall reduction is efa die, and expanded into tight engagementwith 5 fected by cross-rolling over an interiorly disposed the wallsthereof. The expansion is accom mandrel, and enables the production offorgings plished by means of a mandrel which is pushed within very closetolerances. into the die by means of a, press. The foregoing sequence ofoperations involves In application Serial No. 312,499 filed Januarypiercing the slug so that the bore is slightly larger 5, 1940, which hasmatured into Patent N0. lothan that desired in the finished product,placing A. Witter, there is disclosed a method of making sired in thefinished product in the pierced billet. shell forgings and the likewhich accomplishes and exerting pressureon the outer end of the theforegoing with a mandrel which simultanemandrel while the billet isbeing cross-rolled to ously forms a centering cavity. The slug is thenreduce the wall-thickness to an amount slightly partially pierced bymeans of a piercing punch greater than that desired in the finishedproduct, during which the slug is somewhat elongated by and then pushingthe billet and mandrel through the displacement of the metal.Subsequently the a die to make, the final reduction inwall-thickthick-walled partially pierced blank is crossness. It isunderstood, of course, that due allowrolled on a mandrel to reduce thethickness to ance must be made in the mandrel size to comthat requiredin the finished shell forging. pensate for shrinkage of the forgingduring As a result of practicing this process, it has cooling. developedthat while it is very rapid, the forgings One of the problems of shellforging manufaccannot be so made within the tolerances specified ture ismaintaining the interior contour of the for shell forgings. The reasonfor this is that nose portion within the desired tolerances. This boththe inside and outside diameters vary and is overcome by pushing themandrel into the bilthat there are helical undulations in the inside letand by exerting pressure on the back end of surface of the forging. themandrel as the billet passes through the It is an object of the presentinvention to cross-rolls which seats and keeps the point of manufactureshell forgings and the like in a rapid mandrel firmly against the innerend of the billet and economical manner while eliminating the and thusthe desired nose contour is obtained. variations in the diameter andwall-thickness to By leaving the mandrel in the billet during the obtainforgings within very close tolerances. final operation of pushing itthrough the ring The foregoing and other objects will be more or rollerdie this interior contour is maintained, apparent as the followingdescription proceeds. whereas, if a difierent mandrel isused, diincultyAccording to the teachings of the present inis had in getting a mandrelto seat or bottom in vention, a. heated slug of the proper size isexexactly the right place due to scale formation. panded into tightengagement with the walls of a Moreover, by leaving the mandrel inposition and die with the simultaneous formation of a center-- therebycutting down the amount of scaling, ing cavity in the outer end thereof.This opera- 40 working to closer tolerances is permitted. Also, tion isperformed with a mandrel of conventional by using the same mandrel forthe twooperaa closed end tubular blank by the use of a piercsequence,ample time is had for cooling the maning punch which somewhat elongatesthe blank drels which would otherwise become overheatedby extrusion ofthe metal. After this the thickif the fast cycle of operations and highoutput walled partially pierced blank is provided with of which thismethod is capable were maintained. an interiorly disposed mandrel andcross-rolled While I have described one specific embodion a rolling mil1to reduce the wall-thickness apment of the present invention, it will beseen that proximately, but not entirely, to that required in I do notwish to be limited exactly thereto, since the finished shell forging.According to the various modifications may be made'without derolledblank with the interiorly disposed mandrel fined by the following claim.

intact is then pushed through either a ring or a I claim:

roller die (preferably a three-roll roller die). The process ofproducing shell forgings com- Th s fin l p r i n. y slight y d g heoutprising obtaining a closed end blank having a bore of larger diameterthan that desired in the finished diameter, inserting a mandrel having adiameter and contour like that desired in the finished shell forging insaid bore, rolling said blank between cross-rolls to 'reduce thewallthickness thereof to a slightly greater thickness than that desiredin the finished product and the bore to the diameter desired in thefinished product, maintaining pressure on the end of said mandrel whilesaid mandrel and blank are passing through said cross-rolls to obtainthe interior nose contour desired, and subsequently pushing said reducedblank and mandrel through a die to obtain a shell forging having thedesired bore diameter, interior nose contour and the desiredwall-thickness.

STEVENSON FINDLATER.

